At present time, known and promising 3D display technologies based on integral imaging, parallax barrier, volumetric imaging, holography-based techniques, or any combination thereof, etc. have been or are being developed.
The most widely used 3D display technology is a stereo imaging technique providing individual and independent flat images for left and right eyes of a viewer. The left eye can see only “left” images, but cannot see “right” images, and vice versa for the right eye. Such a technique is usually realized by means of glasses, either active or passive. Thus, the demerit of this technique is that additional equipment (i.e. glasses) is required. At the same time, a key issue is that the stereo imaging technique shows a viewer only two flat images without the possibility of parallax control.
There are a lot of different prior art solutions which eliminate the above-indicated drawbacks. One such solution, disclosed in WO 2014133481 A1, provides a multi-view 3D telepresence system including an integral imaging system and a direct view display system. The integral imaging system has a microlens array and a plurality of image sensors to generate a plurality of input image views. The direct view display system has a directional backplane with a plurality of directional pixels to scatter a plurality of input planar light beams into a plurality of directional light beams. The direct view display system also includes a shutter layer for modulating the plurality of directional light beams generated by the plurality of directional pixels. The plurality of directional pixels enables the direct view display system to reproduce the captured images. A viewer can feel as if he or she is present at the time an image is captured, even though the viewer may be many miles away. The viewer is thus able to enjoy full parallax, 3D, and a real-time telepresence experience. In one example, the reproduced images may be displayed at a different scale than the captured images. This may be the case where images are captured in one scale (e.g., microscopic) and displayed at another scale (e.g., full scale or zoomed in). However, the system proposed above is not capable of increasing a 3D screen size and viewing angle and enhancing 3D image quality.
U.S. Pat. No. 7,944,465 B2 describes a system for reproducing 3-dimensional images. The system is based on the integral imaging technique and uses an additional pair of lens rasters with actuators, which provides a 3D display having a sufficiently wide field of view for simultaneous viewing of the 3D display by multiple viewers. However, the system has a limited screen size and limited 3D resolution, and although an additional well-aligned pair of moving rasters included in the system increases viewing area, a current viewing angle value remains the same.
US 20070035512 A1 discloses a 3D image display device using an integral technology that offers a principle of increasing of a 3D viewing angle by using a concave-flat lens raster having an additional material covering the same. The additional material has a refractive index less than that of the lens raster, which leads to extending of the viewing angle of a 3D image. However, the device has a limited screen size and limited 3D resolution.
Thus, there is a need for a glass-free display device capable of increasing image size in at least one direction and providing an increase in image viewing angle and resolution.